Document: draft-ietf-ecrit-security-threats-04.txt
Reviewer: Christian Vogt
Review Date:  July 12, 2007
IETF LC End Date: --
IESG Telechat date: June 21, 2007

Summary:

This document identifies and describes threats that affect emergency
call mechanisms.  As the Requirements document, this document is already
in good shape.  However, as explained below, there is one attack
objective that I think is very important, and that should be attended to
a bit closer.

Comments:

The following attack objective described in the document is important
enough to be attended to a bit closer IMO:

>   o  to divert emergency responders to non-emergency sites. This memo
>      has not identified any attacks within its intended scope that
>      achieve this objective, so it will not be mentioned further.

Diverting emergency responders to non-emergency sites is actually not an
objective that an attacker might have, but rather a technique of
reaching the objective described in the first bullet ("to deny system
services to all users in a given area").  So the draft actually does
address this objective.

Still, I think the /possibility/ for an attacker to divert emergency
responders to non-emergency sites -- as a means of reaching the DoS
objective -- is important enough to get a bit further elaborated on, in
particular with respect to its relationship to the mechanism to be
developed by the Ecrit WG.  I think that some clarification would be
useful along these lines:

Preventing diversion of emergency calls would likely require some
evidence about the existence of a reported emergency case, such as a
photograph, a video clip, or N previous calls reporting the same
emergency case.  The decision of which proof would be acceptable, and
whether requiring such proof is something desirable in the first place,
is likely something that cannot be decided in the Ecrit WG.  Preventing
diversion of emergency calls is hence something that is likely not to be
in scope of the Ecrit WG.

Maybe this should be clarified either in this document, or in the
Requirements document -- in particular because the Requirements document
currently only talks about verifying the caller's location, rather than
verifying whether there actually exists an emergency case at that location.